DE102015011175A1 - Exhaust system for an internal combustion engine - Google Patents

Abstract

The invention relates to an exhaust system (1) for an internal combustion engine, comprising a first exhaust pipe (2), a second exhaust pipe (3) running fluidically parallel to the first exhaust pipe (2), and at least one silencer (5, 6), the first exhaust pipe (2) and the second exhaust pipe (3) emerge from a common exhaust pipe (4). It is provided that the first exhaust pipe (2) is silencer connected to the muffler (6) and the second exhaust pipe (3) through the muffler (6), but is fluidically decoupled from it, wherein a flow cross-section of the second exhaust pipe (3 ) is adjustable by means of a switching valve (12).

Description

The invention relates to an exhaust system for an internal combustion engine, with a first exhaust pipe, a fluidically parallel to the first exhaust pipe extending second exhaust pipe and at least one silencer, wherein the first exhaust pipe and the second exhaust pipe emerge from a common exhaust pipe.

The exhaust system serves to discharge exhaust gas of the internal combustion engine, in particular in the direction of an external environment. The exhaust system is so far on the one hand fluidly connected to the internal combustion engine, preferably via at least one exhaust valve and / or at least one exhaust manifold. The exhaust gas system has several exhaust pipes, namely the first exhaust pipe, the second exhaust pipe and the common exhaust pipe. The first exhaust pipe and the second exhaust pipe run fluidically parallel to each other. Both emerge from the common exhaust pipe. By this is meant that the first exhaust pipe and the second exhaust pipe are arranged downstream of the common exhaust pipe, so that they are fluidly connected via the common exhaust pipe to the internal combustion engine. The exhaust gas generated by the internal combustion engine thus first flows through the common exhaust pipe and is subsequently divided between the first exhaust pipe and the second exhaust pipe. The exhaust system furthermore has the at least one silencer, by means of which sound transmitted by the exhaust gas and generated by the internal combustion engine can be damped or damped.

From the prior art, for example, the publication DE 10 2011 108 059 A1 known. This relates to an exhaust silencer, in particular an end silencer, an internal combustion engine, in particular of a motor vehicle. The exhaust muffler includes a housing made of a material having a lower thermal conductivity than metal, which has an inlet and an outlet for an exhaust pipe. At least one functional component made of plastic, which is part of a device for exhaust gas recirculation of the internal combustion engine, is directly connected to the housing.

It is an object of the invention to propose an exhaust system, which has advantages over known exhaust systems, in particular excellent acoustic properties at the same time has low space.

This is achieved according to the invention with an exhaust system having the features of claim 1. It is provided that the first exhaust pipe is connected to the silencer to dampen the sound and the second exhaust pipe passes through the silencer, but is fluidically decoupled from it, wherein a flow cross section of the second exhaust pipe by means of a switching valve is adjustable.

The first exhaust pipe and the second exhaust pipe are so far both connected to the muffler or run through it. The first exhaust pipe is connected to the silencer to reduce noise. By this is preferably to be understood that the first exhaust pipe opens into an internal volume of the muffler and is interrupted there. Accordingly, the exhaust gas of the internal combustion engine can enter through the first exhaust pipe into the muffler or its inner volume and also exit through the first exhaust pipe again from the muffler or the inner volume. In the muffler itself, however, the exhaust gas can escape from the first exhaust pipe through at least one outlet opening in the inner volume. From the internal volume, it can subsequently enter the first exhaust gas line through at least one inlet opening and be removed from the silencer through the first exhaust gas line.

The outlet opening and the inlet opening of the first exhaust pipe are preferably spaced apart from one another in the muffler or the inner volume. For example, an imaginary plane, in which the inlet opening is located, spaced parallel from an imaginary plane, in which the outlet opening is located. Of course, it can also be provided that the planes are angled against each other, ie an angle of greater than 0 ° and smaller than 180 ° with each other. For example, the outlet opening is assigned to a first partial area of the first exhaust gas line, while the inlet opening is assigned to a second partial area.

It can now be provided that the two subregions are arranged overlapping within the muffler or the inner volume, so at least partially run next to each other. In this case, the subregions or longitudinal central axes of the subregions can be arranged at a distance from one another in parallel or can be angled relative to one another. Of course, however, a plurality of outlet openings and / or a plurality of inlet openings may be provided which are associated with the first exhaust pipe, in particular the first partial area or the second partial area.

While the first exhaust pipe is connected to the silencer in order to dampen noise the second exhaust pipe to pass through the muffler, but be fluidly decoupled from him. This means that the second exhaust pipe runs without interruption through the muffler or the inner volume. Thus, although the second exhaust pipe is partially disposed in the muffler, the exhaust gas flowing through the second exhaust pipe is, however, fluidically completely separated from the inner volume of the muffler. In this respect, no exhaust gas can escape from the second exhaust pipe into the muffler or the inner volume or enter from the muffler into the second exhaust pipe.

In order to adjust the exhaust back pressure in the second exhaust pipe, the switching valve is provided. By means of this, the flow cross section of the second exhaust pipe is adjustable. The switching valve can be designed as a discrete switching valve or as a continuous valve. By adjusting the flow cross-section of the second exhaust pipe, the exhaust gas flowing through the common exhaust pipe can be optionally split between the first exhaust pipe, the second exhaust pipe, or both exhaust pipes. In that regard, it can be influenced by means of the switching valve on which proportion of the exhaust gas of the muffler acts sound-absorbing. Accordingly, the noise of the engine can be influenced by means of the switching valve.

In a further embodiment of the invention, it is provided that the switching valve is present as an exhaust gas recirculation valve and branches off upstream of the switching valve, an exhaust gas recirculation line from the second exhaust pipe or the common exhaust pipe. Because the exhaust backpressure in the second exhaust gas line can be influenced by means of the switching valve, not only is it possible to influence the background noise of the internal combustion engine, but also to influence a mass flow of exhaust gas to be returned to the internal combustion engine. With the help of the exhaust system, therefore, an exhaust gas recirculation can be realized. For this purpose, upstream of the switching valve branches off the exhaust gas recirculation line from the second exhaust pipe or the common exhaust pipe.

If the second exhaust gas line is completely blocked by means of the switching valve, ie the flow cross section is equal to zero or at least almost zero, then the pressure in the exhaust gas recirculation line corresponds to the exhaust backpressure present in the first exhaust gas line, which is decisively determined by the silencer. Because the second exhaust pipe is fluidically decoupled from the muffler, the second exhaust pipe causes a lower pressure loss than the first exhaust pipe. In that regard, when completely released second exhaust pipe, ie at maximum flow cross-section, the exhaust back pressure or present in the exhaust gas recirculation exhaust pressure is lower than at least partially obstructed exhaust pipe. The exhaust gas pressure required for the return of the exhaust gas in the exhaust gas recirculation line is preferably greater than the exhaust gas pressure present when the second exhaust line is fully released and smaller than the exhaust gas pressure present when the second exhaust line is completely blocked.

A development of the invention provides that the switching valve is present downstream of the muffler. In principle, the switching valve in the flow direction of the exhaust gas can be arranged arbitrarily on or in the second exhaust pipe. Preferably, however, it is located downstream of the muffler.

A further embodiment of the invention provides that the muffler is designed as a rear muffler. The muffler is insofar as in the flow direction last silencer of the exhaust system before.

Downstream of the muffler, the exhaust gas flows into the outside environment of the exhaust system, in particular through a tailpipe.

In a further preferred embodiment of the invention it is provided that at least one further silencer is provided upstream of the silencer, wherein the first exhaust pipe is connected to the other silencer sound-absorbing and the second exhaust pipe passes through the further silencer, but is fluidically decoupled from him. The muffler is so far not the only muffler of the exhaust system. although this may be the case. Rather, the exhaust system has several mufflers, in particular a variety of mufflers. The at least one further silencer is connected in a sound-damping manner to the first exhaust pipe analogous to the above explanations for the silencer. By contrast, the second exhaust pipe runs fluidically away from it through it. Thus, although the further muffler influenced the pressure loss caused by the first exhaust pipe, but not the present in the second exhaust pipe.

In a further preferred embodiment of the invention, it is provided that the first exhaust pipe causes a higher pressure loss than the second exhaust pipe with open switching valve. This has already been pointed out above. Thus, if the second exhaust pipe of the switching valve is fully released, so that the flow cross-section is maximum, so should in the second Exhaust pipe, a lower pressure loss than in the first exhaust pipe, wherein the pressure loss of the first exhaust pipe is substantially influenced by the muffler or the at least one further muffler.

A further embodiment of the invention provides that the switching valve is designed as a discrete switching valve or as a continuous valve. This has already been pointed out above. The discretely switching valve preferably has only two states, wherein in one of the states, the second exhaust gas line is fully released at maximum flow cross-section and completely blocked in a further one of the states with a minimum flow cross-section. In contrast, the continuous valve makes it possible to set numerous different flow cross-sections of the second exhaust pipe.

It is particularly preferably provided in a further embodiment that in the first exhaust pipe and / or the second exhaust pipe in each case an exhaust aftertreatment device is present. The exhaust aftertreatment device can be designed, for example, as a catalyst or as a diesel particle filter. Of course, in each case a plurality of such exhaust aftertreatment devices may be provided in the first exhaust pipe and / or the second exhaust pipe.

A development of the invention provides that downstream of the switching valve, a sound pipe opens into the second exhaust pipe. Using the sound tube, the noise of the engine can be actively influenced. For example, a sonic space is fluidically connected to the second exhaust pipe via the sound pipe, wherein in the sound space preferably a speaker is provided. In this respect, a vibration can be impressed on the exhaust gas flowing through the second exhaust pipe via the sound pipe, in particular by appropriate control of the loudspeaker.

Finally, it can be provided in a further preferred embodiment of the invention that the first exhaust pipe and the second exhaust pipe discharge downstream of the muffler in separate tailpipes. About the tailpipes, the first exhaust pipe and the second exhaust pipe are directly connected to the outside environment. This means that one of the tailpipes is connected on the one hand to the first exhaust pipe and on the other hand to the outside environment, while a second of the tailpipes is connected on the one hand to the second exhaust pipe and on the other hand to the outside environment. The tailpipe thus exits directly into the outside environment via the tailpipes. Accordingly, it is not intended to merge the exhaust gas flowing through the first exhaust pipe and the second exhaust pipe before discharging into the outside environment. Rather, this only happens in the outdoor environment.

The invention will be explained in more detail with reference to the embodiments illustrated in the drawings, without any limitation of the invention. Showing:

1 a schematic representation of a portion of an exhaust system for an internal combustion engine, and

2 a detailed view of a muffler of the exhaust system.

The 1 shows a schematic representation of an exhaust system 1 for an internal combustion engine. The exhaust system 1 has a first exhaust pipe 2 and a second exhaust pipe 3 on. Both exhaust pipes 2 and 3 go out of a common exhaust pipe 4 through which they are fluidly connected to the internal combustion engine. Furthermore, the exhaust system has 1 via at least one silencer, in the exemplary embodiment illustrated here, via two silencers 5 and 6 , The silencer 6 is designed as a rear silencer. Downstream of the muffler 6 therefore lead the exhaust pipes 2 and 3 each in a tailpipe 7 respectively 8th a, over which in the respective exhaust pipe 2 respectively 3 flowing exhaust gas of an outdoor environment 9 is supplied. It may optionally be provided that in the exhaust pipes 2 and 3 each an exhaust aftertreatment device 10 respectively 11 is present. The exhaust aftertreatment device 10 and 11 can be configured for example as a catalyst or as a particle filter.

It can be clearly seen that the exhaust pipes 2 and 3 each through both silencers 5 and 6 pass through. However, only the first exhaust pipe is 2 sound-absorbing to the silencers 5 and 6 connected. The second exhaust pipe 3 Although passes through the muffler 5 and 6 , but is fluidically decoupled from them. This means, on the one hand, that vibrations in the first exhaust pipe 2 flowing exhaust gas by means of the muffler 5 and 6 be attenuated stronger than those in the second exhaust pipe 3 flowing exhaust gas. On the other hand, the silencers cause 5 and 6 in the first exhaust pipe 2 each a pressure drop, so that the first exhaust pipe 2 as a whole has a higher pressure loss than the second exhaust pipe 3 ,

A flow cross section of the second exhaust pipe 3 is preferably by means of a switching valve 12 adjustable. Using the switching valve 12 can the extent of the pressure drop of the second exhaust pipe 3 and thus in the second exhaust pipe 3 occurring exhaust back pressure can be adjusted. The switching valve 12 may for example be designed as a discrete switching valve or as a continuous valve. Purely optionally, it may be provided that a sound tube 13 downstream of the muffler 6 or both silencers 5 and 6 but preferably upstream of the tailpipe 8th , in the second exhaust pipe 3 opens. For example, over the sound pipe 13 a sound room 14 with the second exhaust pipe 3 fluidly connected, wherein in the sound space 14 a speaker or the like may be arranged. About the sound tube 13 this can be the second exhaust pipe 3 flowing exhaust gas are subjected to vibrations, so that the background noise of the internal combustion engine can be influenced.

Upstream of the switching valve 12 branches from the second exhaust pipe 3 or the common exhaust pipe 4 an exhaust gas recirculation line 15 from. This is shown here purely by way of example. In particular, the exhaust gas recirculation line branches upstream of the muffler 5 and 6 from the second exhaust pipe 3 from.

The 2 shows a detailed representation of the muffler 5 , However, the following explanations are readily on the muffler 6 transferable. It becomes clear that the muffler 5 an internal volume 16 having, that of a housing shell 17 , In particular of two attached housing shells 17 , fluid-tight against the outside environment 9 is closed. It can be seen that the first exhaust pipe 2 sound-absorbing to the muffler 5 connected. For this purpose, the first exhaust pipe 2 for example, a first subarea 18 as well as a second subarea 19 on, with both subregions 18 and 19 completely within the interior volume 16 are arranged. The subareas 18 and 19 However, they are not directly fluidly connected to each other, but only indirectly via the internal volume 16 ,

Accordingly, that occurs the first exhaust pipe 2 supplied exhaust gas within the muffler 5 from the first section 18 in the interior volume 16 to go to the second subsection below 19 enter. Then the exhaust gas passes through the first exhaust pipe 2 or their second subarea 19 from the muffler 5 out and in the direction of the outside environment 9 dissipated. The second exhaust pipe 3 is also in the muffler 5 or in its internal volume 16 arranged. However, it runs continuously, so that they fluidically completely from the internal volume 16 is disconnected. In the second exhaust pipe 3 flowing exhaust gas can not so far in the internal volume 16 emerge or in the internal volume 16 Exhaust gas is not in the second exhaust pipe 3 enter.

By such a configuration of the exhaust system 1 lie in the exhaust pipes 2 and 3 different exhaust back pressures before when the second exhaust pipe 3 by means of the switching valve 12 is completely released. With released second exhaust pipe 3 Preferably, the exhaust gas flows through it. By means of the switching valve 12 can now do that via the common exhaust pipe 4 guided exhaust gas on the first exhaust pipe 2 and the second exhaust pipe 3 be split. Accordingly, on the one hand, the noise of the engine and on the other hand, the mass flow of the recirculated into the engine exhaust gas by means of the switching valve 12 be set.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011108059 A1 [0003]

Claims (10)

Exhaust system for an internal combustion engine, with a first exhaust pipe ( 2 ), a fluidic parallel to the first exhaust pipe ( 2 ) extending second exhaust pipe ( 3 ) and at least one silencer ( 5 . 6 ), wherein the first exhaust pipe ( 2 ) and the second exhaust pipe ( 3 ) from a common exhaust pipe ( 4 ), characterized in that the first exhaust pipe ( 2 ) silencing the muffler ( 6 ) and the second exhaust pipe ( 3 ) through the muffler ( 6 ), but is fluidically decoupled from it, wherein a flow cross-section of the second exhaust pipe ( 3 ) by means of a switching valve ( 12 ) is adjustable. Exhaust system according to claim 1, characterized in that the switching valve ( 12 ) exists as an exhaust gas recirculation valve and upstream of the switching valve ( 12 ) an exhaust gas return line ( 15 ) from the second exhaust pipe ( 3 ) or common exhaust pipe ( 4 ) branches off. Exhaust system according to one of the preceding claims, characterized in that the switching valve ( 12 ) downstream of the muffler ( 6 ) is present. Exhaust system according to one of the preceding claims, characterized in that the silencer ( 6 ) is designed as a rear silencer. Exhaust system according to one of the preceding claims, characterized in that upstream of the muffler ( 6 ) at least one additional silencer ( 5 ) is provided, wherein the first exhaust pipe ( 2 ) silencer to the other silencer ( 5 ) and the second exhaust pipe ( 3 ) through the further silencer ( 5 ), but is fluidically decoupled from him. Exhaust system according to one of the preceding claims, characterized in that the first exhaust pipe ( 2 ) causes a higher pressure loss than the second exhaust pipe ( 3 ) with open switching valve ( 12 ). Exhaust system according to one of the preceding claims, characterized in that the switching valve ( 12 ) is designed as a discrete switching valve or as a continuous valve. Exhaust system according to one of the preceding claims, characterized in that in the first exhaust pipe ( 2 ) and / or the second exhaust pipe ( 3 ) each an exhaust aftertreatment device ( 10 . 11 ) is present. Exhaust system according to one of the preceding claims, characterized in that downstream of the switching valve ( 12 ) a sound tube ( 13 ) in the second exhaust pipe ( 3 ). Exhaust system according to one of the preceding claims, characterized in that the first exhaust pipe ( 2 ) and the second exhaust pipe ( 3 ) downstream of the muffler ( 6 ) in separate tailpipes ( 7 . 8th ).

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